10 M. H. Herwig on the Disintegration of the 



Negative electrode iron, lost 5 "5 milligr. iron, took up 1 mil- 

 ligr. copper. 



The longer of these experiments had to be performed with 

 short intermissions, in order not to heat the electrodes to fusion. 

 As very small quantities were in question, the chemical analysis 

 was of course cautiously effected, and was only applied to the 

 superficial layers of the electrodes, these being the only ones 

 concerned. Since, in spite of the extreme rarefaction of the air 

 in the cylinder, a few small portions on the electrodes (especially 

 the particles of other metals precipitated upon them) were some- 

 times found to be oxidized, this slight content of oxygen had to 

 be taken into account in the analyses. Although under these 

 circumstances the numbers given present little uncertainties, yet 

 they cannot be affected with gross errors ; and therefore we have 

 in them a satisfactorily approximate representation of the pro- 

 portions. 



Therefrom these proportions are perceived to be absolutely 

 irregular. Even when the same metals are employed respectively 

 for the positive and for the negative electrodes in different expe- 

 riments, they give sometimes equal loss at' both electrodes, some- 

 times more at the positive, and sometimes more at the negative 

 electrode. There is likewise visible no connexion with the amount 

 of hydrogen simultaneously developed. The only regularly oc- 

 curring circumstance in these, as in all my experiments, was, 

 that the heating of the positive electrode was always the quickest, 

 and it was the first to become red-hot; but this circumstance, 

 in the case of two electrodes of the same kind, is universally 

 known. 



Now, it seems, a cause can at once be adduced which contains 

 a partial explanation of this irregularity. The experiments above 

 given show that, although a brisk scattering of the disintegrated 

 metallic particles in all directions always takes place, and in con- 

 sequence of this a more or less dense precipitate of powder is 

 always seen on the neighbouring sides of the cylinder, yet a not 

 inconsiderable portion of the metal lost by one electrode may often 

 be found on the other. Such portions of the foreign metal are 

 firmly melted to the electrode on which they are seated. Now, 

 supposing an experiment in which this has taken place continued, 

 doubtless one of those portions might again be subjected to 

 disintegration, since it is situated in the front, the part most 

 affected by it ; and thus the act of disintegration would have been 

 employed more than once upon the same metallic particles. 

 That such a behaviour actually played a part in the experiments 

 here discussed is shown by several observations. For example, 

 in experiment 1 the 3 milligr. of copper taken up by the iron 

 electrode was not on its surface, but under a thin layer of iron, 



